CN113544156A

CN113544156A - anti-Claudin18.2 antibody and application thereof

Info

Publication number: CN113544156A
Application number: CN202080019073.9A
Authority: CN
Inventors: 杨阳; 葛虎; 陶维康
Original assignee: Jiangsu Hengrui Medicine Co Ltd; Shanghai Hengrui Pharmaceutical Co Ltd
Current assignee: Jiangsu Hengrui Medicine Co Ltd; Shanghai Hengrui Pharmaceutical Co Ltd
Priority date: 2019-04-01
Filing date: 2020-03-31
Publication date: 2021-10-22
Anticipated expiration: 2040-03-31
Also published as: CA3134411A1; MX2021011489A; EP3950716A4; ZA202106880B; KR20210148216A; TW202102546A; JP7592022B2; CN116063516A; JP2022528061A; AU2020250601A1; TWI848090B; WO2020200196A1; US20220185881A1; CN113544156B; EP3950716A1; BR112021019135A2

Abstract

The present disclosure relates to anti-Claudin18.2 antibodies and uses thereof. Specifically, the present invention relates to an anti-Claudin18.2 antibody; murine antibodies, chimeric antibodies, humanized antibodies and antigen-binding fragments thereof comprising the CDRs of the anti-Claudin18.2 antibody, and their use as medicines. In particular, the present disclosure relates to the use of an anti-Claudin18.2 antibody in the manufacture of a medicament for the treatment of a Claudin18.2 positive disease or condition.

Description

anti-Claudin18.2 antibody and application thereof

This application claims priority to chinese patent application 201910257853.6 filed on 1/4/2019, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the field of antibody pharmaceuticals. In particular, the disclosure relates to claudin18.2 antibodies and uses thereof.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Claudin18 (Claudin-18, CLDN18) is a protein encoded by the Claudin18 gene in humans, and belongs to the family of cell Claudin proteins. Claudin-18 may control the molecular flow between the layers of cells.

The structure of Claudin-18 protein includes four transmembrane regions, two extracellular loops, with the N-terminus and C-terminus being cytoplasmic. Claudin-18 has two splice variants, Claudin 18.1 and Claudin18.2, respectively, with eight amino acid differences between the two sequences only in the first extracellular loop. The expression profiles of Claudin 18.1 and Claudin18.2 are different, Claudin 18.1 is selectively expressed in cells of normal lung, and Claudin18.2 is highly restricted in expression in normal cells, but frequently activated ectopically and overexpressed in various tumors (gastric cancer, lung cancer, pancreatic cancer and the like). Claudin18.2 is considered as a potential therapeutic target of gastric cancer and other cancer types, and the discovery of the target also provides a new choice for the treatment of gastric cancer.

Disclosure of Invention

The present disclosure provides an anti-claudin18.2 antibody.

In some embodiments, the anti-claudin18.2 antibody, as described previously, comprises a heavy chain variable region and a light chain variable region, wherein:

i) the heavy chain variable region comprises a heavy chain variable region and a heavy chain variable region as set forth in SEQ ID NO:3, and a light chain variable region comprising HCDR1, HCDR2, and HCDR3 having the same sequence as the heavy chain variable region set forth in SEQ ID NO:4, LCDR1, LCDR2 and LCDR3 having the same sequence as the light chain variable region; or

ii) the heavy chain variable region comprises a sequence identical to the sequence set forth in SEQ ID NO:5, and a light chain variable region comprising HCDR1, HCDR2, and HCDR3 having the same sequence as the heavy chain variable region set forth in SEQ ID NO:6, LCDR1, LCDR2 and LCDR 3. In some embodiments, the anti-claudin18.2 antibody, as described previously, comprises a heavy chain variable region and a light chain variable region, wherein:

iii) the heavy chain variable region comprises the amino acid sequences as set forth in SEQ ID NOs: 9. SEQ ID NO: 10 and SEQ ID NO: 11, and HCDR1, HCDR2 and HCDR3, the light chain variable region comprising amino acid sequences set forth in SEQ ID NOs: 12. SEQ ID NO: 13 and SEQ ID NO: LCDR1, LCDR2 and LCDR3 shown at 14; or

iv) the heavy chain variable region comprises the amino acid sequences as set forth in SEQ ID NOs: 15. SEQ ID NO: 16 and SEQ ID NO: 17, and HCDR1, HCDR2 and HCDR3, wherein the light chain variable region comprises the amino acid sequences set forth in SEQ ID NOs: 18. SEQ ID NO: 19 and SEQ ID NO: LCDR1, LCDR2 and LCDR3 shown at 20.

It will be understood by those skilled in the art that item numbers, e.g., i), ii), a), b), etc., are used solely to make the listed items or elements clearer and more organized, but are not meant to be restrictive in any way as to the items or elements that follow. When the same item number is used, it does not mean that the technical solution or elements following it are the same.

In some embodiments, the anti-claudin 18.2 antibody is as previously described, wherein said anti-claudin 18.2 antibody is a murine, chimeric or humanized antibody.

(v) the heavy chain variable region has at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the heavy chain variable region of SEQ ID NO 3 or 24, and the light chain variable region has at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the light chain variable region of SEQ ID NO 4 or 21; or

(vi) The heavy chain variable region has at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the heavy chain variable region of SEQ ID NO 5 or 31, and the light chain variable region has at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the light chain variable region of SEQ ID NO 6 or 28.

(1) the heavy chain variable region amino acid sequence is shown as SEQ ID NO. 3 or has at least 90% identity therewith, and the light chain variable region amino acid sequence is shown as SEQ ID NO. 4 or has at least 90% identity therewith;

(2) the heavy chain variable region amino acid sequence is shown as SEQ ID NO. 24 or has at least 90% identity therewith, and the light chain variable region amino acid sequence is shown as SEQ ID NO. 21 or has at least 90% identity therewith;

(3) the heavy chain variable region amino acid sequence is shown as SEQ ID NO. 5 or has at least 90% identity therewith, and the light chain variable region amino acid sequence is shown as SEQ ID NO. 6 or has at least 90% identity therewith; or

(4) The heavy chain variable region amino acid sequence is shown as SEQ ID NO. 31 or has at least 90% identity therewith, and the light chain variable region amino acid sequence is shown as SEQ ID NO. 28 or has at least 90% identity therewith.

In some embodiments, the anti-claudin 18.2 antibody as described previously, wherein said anti-claudin 18.2 antibody is a humanized antibody comprising a framework region derived from a human antibody or a framework region variant thereof, said framework region variant having a back mutation of up to 10 amino acids on the light chain framework region and/or the heavy chain framework region, respectively, of a human antibody.

In some embodiments, the heavy chain framework region of the human antibody is identical to the framework region of the heavy chain variable region represented by amino acid sequence SEQ ID NO. 24, or the light chain variable region of the human antibody is identical to the framework region of the light chain variable region represented by amino acid sequence SEQ ID NO. 21; or the framework region of the heavy chain of the human antibody is identical to the framework region of the heavy chain variable region represented by the amino acid sequence SEQ ID NO. 31, or the framework region of the light chain variable region of the human antibody is identical to the framework region of the light chain variable region represented by the amino acid sequence SEQ ID NO. 28.

In some embodiments, preferably, the framework region variant comprises a mutation selected from (a) or (b) below:

(a) the light chain variable region comprises one or more amino acid back mutations in 22S, 85I or 87H, and/or the heavy chain variable region comprises one or more amino acid back mutations selected from 48I, 82T and 69M; or

(b) The light chain variable region comprises one or more amino acid back mutations selected from 4L and 22S, and/or the heavy chain variable region comprises one or more amino acid back mutations selected from 38K, 40R, 48I, 66K, 67A, 69L, 71L and 73K.

In some embodiments, the framework region variant comprises a mutation selected from the group consisting of the mutations described in (a-1) or (b-1) below, as described previously for the anti-Claudin18.2 antibody:

(a-1) amino acid back mutations comprising 22S, 85I and 87H in the light chain variable region and 48I and 82T in the heavy chain variable region; or

(b-1) the light chain variable region comprises a back mutation of an amino acid selected from 4L.

In some embodiments, the anti-claudin18.2 antibody is as previously described, wherein:

(vii) the heavy chain variable region sequence is shown as SEQ ID NO 3 and the light chain variable region sequence is shown as SEQ ID NO:4 is shown in the specification; or

(viii) The heavy chain variable region sequence is shown as SEQ ID NO 24, 25, 26 or 27 and the light chain variable region sequence is shown as SEQ ID NO: 21. 22 or 23; or

(ix) The heavy chain variable region sequence is shown as SEQ ID NO:5 and the light chain variable region sequence is shown as SEQ ID NO:6 is shown in the specification; or

(x) The heavy chain variable region sequence is shown as SEQ ID NO 31, 32, 33 or 34 and the light chain variable region sequence is shown as SEQ ID NO: 28. 29 or 30.

In some embodiments, the anti-claudin18.2 antibody is as previously described, wherein: the anti-claudin18.2 antibody, or antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region as shown below:

(xi) The heavy chain variable region sequence is shown as SEQ ID NO. 31 and the light chain variable region sequence is shown as SEQ ID NO. 29; or

(xii) The heavy chain variable region sequence is shown as SEQ ID NO. 26 and the light chain variable region sequence is shown as SEQ ID NO. 23.

In some embodiments, the anti-claudin18.2 antibody is as previously described, wherein: the light chain variable region and the heavy chain variable region may be a combination of light chain and heavy chain variable regions as shown in the following table:

TABLE 1 mAb1901 humanized antibody light and heavy chain variable region combinations

Variable region	VH1	VH2	VH3	VH4
VL1	VH1VL1	VH2VL1	VH3VL1	VH4VL1
VL2	VH1VL2	VH2VL2	VH3VL2	VH4VL2
VL3	VH1VL3	VH2VL3	VH3VL3	VH4VL3

TABLE 2 mAb1902 humanized antibody light and heavy chain variable region combinations

Variable region	VH11	VH12	VH13	VH14
VL11	VH11VL11	VH12VL11	VH13VL11	VH14VL11
VL12	VH11VL12	VH12VL12	VH13VL12	VH14VL12
VL13	VH11VL13	VH12VL13	VH13VL13	VH14VL13

In some embodiments, the anti-claudin18.2 antibody, as described previously, wherein said antibody further comprises an antibody constant region. In some specific embodiments, the heavy chain constant region of the antibody is selected from human IgG1, IgG2, IgG3, and IgG4 constant regions and variants thereof, and the light chain constant region of the antibody is selected from human kappa and lambda chain constant regions and variants thereof. In some specific embodiments, the antibody comprises a heavy chain constant region having the sequence shown in SEQ ID NO. 7 and a light chain constant region having the sequence shown in SEQ ID NO. 8. In some specific embodiments, the antibody comprises: a heavy chain having at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the amino acid sequence shown in SEQ ID NO. 35 or 42 and a light chain having at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the amino acid sequence shown in SEQ ID NO. 36 or 39; or

A heavy chain having at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the amino acid sequence shown in SEQ ID NO 37 or 49 and/or a light chain having at least 90%, 92%, 94%, 95%, 96%, 97%, 98%, 99%, 100% identity to the amino acid sequence shown in SEQ ID NO 38 or 46.

In some embodiments, the anti-claudin18.2 antibody, as described previously, comprises:

(c) 35 and/or a heavy chain with a sequence shown as SEQ ID NO:36, a light chain;

(d) 42, 43, 44 or 45 and/or a heavy chain having the sequence shown in SEQ ID NO: 39. 40 or 41;

(e) 37 and/or a heavy chain with a sequence shown as SEQ ID NO: 38; or

(f) 49, 50, 51 or 52 and/or a heavy chain having the sequence shown in SEQ ID NO: 46. 47 or 48.

In some embodiments, the anti-claudin 18.2 antibody, as described previously, competes with the aforementioned anti-claudin 18.2 antibody or antigen-binding fragment thereof for binding to human claudin 18.2.

a heavy chain with an amino acid sequence shown as SEQ ID NO. 44 and a light chain with a sequence shown as SEQ ID NO. 41; or

A heavy chain with an amino acid sequence shown as SEQ ID NO. 49, and a light chain with a sequence shown as SEQ ID NO. 47.

Yet another aspect of the disclosure provides a nucleic acid molecule encoding the anti-claudin18.2 antibody as described previously.

Yet another aspect of the disclosure provides an expression vector comprising a nucleic acid molecule as described above.

Yet another aspect of the present disclosure provides a host cell comprising a nucleic acid molecule as described above or an expression vector as described above, preferably the cell is a bacterial cell, a fungal cell, an insect animal cell or a mammalian cell.

Yet another aspect of the present disclosure provides an antibody drug conjugate formed by coupling an anti-claudin 18.2 antibody according to the preceding description with a cytotoxic drug.

Yet another aspect of the present disclosure provides an antibody drug conjugate comprising or consisting of: the aforementioned anti-claudin18.2 antibody covalently bound to a cytotoxic drug.

In some embodiments, the present disclosure provides a method of making the claudin18.2 antibody as previously described.

In some embodiments, the present disclosure provides a method of making a claudin18.2 antibody drug conjugate, as previously described.

In some embodiments, the present disclosure provides a pharmaceutical composition comprising a therapeutically effective amount of an anti-claudin 18.2 antibody according to the preceding description, or a nucleic acid molecule according to the preceding description, or an antibody drug conjugate according to the preceding description, and one or more pharmaceutically acceptable carriers, diluents, buffers or excipients.

In some embodiments, the present disclosure provides a method for the immunodetection or assay of claudin18.2, comprising the step of contacting a test sample with an anti-claudin 18.2 antibody as previously described.

In some embodiments, the present disclosure provides the use of an anti-claudin 18.2 antibody, as described previously, in the preparation of a reagent for the immunological detection of human claudin 18.2.

In some embodiments, the present disclosure provides an anti-claudin 18.2 antibody as previously described for use in an immunoassay or assay for claudin 18.2.

In some embodiments, the present disclosure provides a kit comprising an anti-claudin18.2 antibody according to the preceding description.

In some embodiments, the present disclosure provides the use of an anti-claudin 18.2 antibody, or a nucleic acid molecule, or an antibody drug conjugate, or a pharmaceutical composition, as described above, in the manufacture of a medicament for the treatment of a cancer or tumor, preferably a claudin18.2 positive cancer or malignancy, more preferably a head and neck squamous cell carcinoma, head and neck cancer, brain cancer, glioma, glioblastoma multiforme, neuroblastoma, central nervous system cancer, neuroendocrine tumor, pharyngeal and laryngeal cancer, nasopharyngeal cancer, esophageal cancer, thyroid cancer, malignant pleural mesothelioma, lung cancer, breast cancer, liver cancer, hepatoma, hepatocellular carcinoma, hepatobiliary cancer, pancreatic cancer, gastric cancer, gastrointestinal cancer, intestinal cancer, colon cancer, colorectal cancer, kidney cancer, clear cell renal cell carcinoma, ovarian cancer, endometrial cancer, colon cancer, or a method for the treatment of the human skin, or a subject, Cervical cancer, bladder cancer, prostate cancer, testicular cancer, skin cancer, melanoma, leukemia, lymphoma, bone cancer, chondrosarcoma, myeloma, multiple myeloma, myelodysplastic syndrome, myeloproliferative neoplasm, squamous cell carcinoma, ewing's sarcoma, systemic light chain amyloidosis, and merkel cell carcinoma; the lymphoma is selected from: hodgkin's lymphoma, non-Hodgkin's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, primary mediastinal large B-cell lymphoma, mantle cell lymphoma, small lymphocytic lymphoma, large B-cell lymphoma enriched in T-cells/histiocytes, and lymphoplasmacytic lymphoma, said lung cancer being selected from the group consisting of: non-small cell lung cancer and small cell lung cancer, said leukemia being selected from: chronic myeloid leukemia, acute myeloid leukemia, lymphocytic leukemia, lymphoblastic leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, and myeloid leukemia.

In some embodiments, the present disclosure provides a method of treating a disease associated with claudin18.2, comprising administering to a subject a therapeutically effective amount of an anti-claudin 18.2 antibody, as described previously, or a nucleic acid molecule, as described previously, or an antibody drug conjugate, as described previously, or a pharmaceutical composition, as described previously, wherein the disease is preferably a cancer or a tumor; more preferably a claudin18.2 positive cancer or malignancy, more preferably selected from: head and neck squamous cell carcinoma, head and neck cancer, brain cancer, glioma, glioblastoma multiforme, neuroblastoma, central nervous system cancer, neuroendocrine tumor, throat cancer, nasopharyngeal cancer, esophageal cancer, thyroid cancer, malignant pleural mesothelioma, lung cancer, breast cancer, liver cancer, hepatoma, hepatocellular carcinoma, hepatobiliary cancer, pancreatic cancer, gastric cancer, gastrointestinal cancer, intestinal cancer, colon cancer, colorectal cancer, kidney cancer, clear cell renal cell carcinoma, ovarian cancer, endometrial cancer, cervical cancer, bladder cancer, prostate cancer, testicular cancer, skin cancer, melanoma, leukemia, lymphoma, bone cancer, chondrosarcoma, myeloma, multiple myeloma, myelodysplastic syndrome, myeloproliferative tumors, squamous cell carcinoma, ewing's sarcoma, systemic light chain amyloidosis, and merkel cell carcinoma. More preferably, the lymphoma is selected from: hodgkin's lymphoma, non-Hodgkin's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, primary mediastinal large B-cell lymphoma, mantle cell lymphoma, small lymphocytic lymphoma, large B-cell lymphoma enriched in T-cells/histiocytes, and lymphoplasmacytic lymphoma, said lung cancer being selected from the group consisting of: non-small cell lung cancer and small cell lung cancer, said leukemia being selected from: chronic myeloid leukemia, acute myeloid leukemia, lymphocytic leukemia, lymphoblastic leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, and myeloid leukemia.

In some embodiments, the therapeutically effective amount is a unit dose of the composition comprising from 0.1mg to 3000mg or from 1mg to 1000mg of the anti-claudin 18.2 antibody as previously described or the antibody drug conjugate as previously described.

In some embodiments, the present disclosure provides an anti-claudin 18.2 antibody as described hereinbefore, or a nucleic acid molecule as described hereinbefore, or an antibody drug conjugate as described hereinbefore or a pharmaceutical composition as described hereinbefore for use in the treatment of a disease associated with claudin18.2, wherein the disease is preferably a cancer or a tumor; more preferably a claudin18.2 positive cancer or malignancy, more preferably selected from: head and neck squamous cell carcinoma, head and neck cancer, brain cancer, glioma, glioblastoma multiforme, neuroblastoma, central nervous system cancer, neuroendocrine tumor, throat cancer, nasopharyngeal cancer, esophageal cancer, thyroid cancer, malignant pleural mesothelioma, lung cancer, breast cancer, liver cancer, hepatoma, hepatocellular carcinoma, hepatobiliary cancer, pancreatic cancer, gastric cancer, gastrointestinal cancer, intestinal cancer, colon cancer, colorectal cancer, kidney cancer, clear cell renal cell carcinoma, ovarian cancer, endometrial cancer, cervical cancer, bladder cancer, prostate cancer, testicular cancer, skin cancer, melanoma, leukemia, lymphoma, bone cancer, chondrosarcoma, myeloma, multiple myeloma, myelodysplastic syndrome, myeloproliferative tumors, squamous cell carcinoma, ewing's sarcoma, systemic light chain amyloidosis, and merkel cell carcinoma. More preferably, the lymphoma is selected from: hodgkin's lymphoma, non-Hodgkin's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, primary mediastinal large B-cell lymphoma, mantle cell lymphoma, small lymphocytic lymphoma, large B-cell lymphoma enriched in T-cells/histiocytes, and lymphoplasmacytic lymphoma, said lung cancer being selected from the group consisting of: non-small cell lung cancer and small cell lung cancer, said leukemia being selected from: chronic myeloid leukemia, acute myeloid leukemia, lymphocytic leukemia, lymphoblastic leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, and myeloid leukemia.

In some embodiments, the cancer is gastric cancer, esophageal cancer, lung cancer, pancreatic cancer.

In some embodiments, the antibodies, antibody drug conjugates as described above can play a therapeutic role in cancers as described above with high, medium, and low expression of claudin 18.2.

The Claudin18.2 antibody and the antibody drug conjugate provided by the disclosure have good affinity with a cell surface antigen, good endocytosis efficiency and strong tumor inhibition efficiency, have a wider drug application window, and are suitable for clinical drug application.

Drawings

FIG. 1: FACS detection of binding of humanized antibody to human claudin18.2 at cellular level.

FIG. 2: NUGC4 endocytosis experiments of humanized antibodies.

Fig. 3A to 3C: the ADCC effect of the antibody was detected in NUGC4 cells with different degrees of Claudin18.2 expression. FIG. 3A is a graph showing ADCC effect detection of antibodies in wild-type NUGC4 cells (low expression of Claudin18.2); FIG. 3B is a graph showing the ADCC effect of antibodies in cells expressing NUGC4 on Claudin18.2; FIG. 3C is a graph showing the ADCC effect of the antibody in cells with Claudin18.2 high expression of NUGC 4.

Detailed Description

Term(s) for

In order that the disclosure may be more readily understood, certain technical and scientific terms are specifically defined below. Unless otherwise specifically defined herein, all other technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

The three letter codes and the one letter codes for amino acids used in this disclosure are as described in j. diol. chem, 243, p3558 (1968).

The term "cytotoxic drug" refers to a substance that inhibits or prevents the function of a cell and/or causes cell death or destruction. Including toxins, chemotherapeutic agents, and the like, can be used to kill cells.

The term "toxin" refers to any substance capable of exerting a deleterious effect on the growth or proliferation of cells and may be a small molecule toxin from bacteria, fungi, plants or animals and derivatives thereof, including camptothecin derivatives such as isatorin, maytansinoids and derivatives thereof (CN101573384) such as DM1, DM3, DM4, orlistatin f (af) and derivatives thereof such as MMAF, MMAE, 3024(WO 2016/127790a1, compound 7), diphtheria toxin, exotoxin, ricin (ricin) a chain, abrin (abrin) a chain, modecin, α -sarcin (sarcin), aleurites fordii (aleutides fordii) toxic protein, carnation (dianthin) toxic protein, phytolacca (phytolacca americana) toxic protein (PAPI, PAPII and PAP-S), morinda officinalis (morica) inhibitory protein, matricaria (balsamifera) toxic protein, crotin inhibitory protein (crotamifera), crotoncha officinalis inhibitory protein (croton officinalis), croton officinalis (croton officinalis) toxic, croton officinalis (crassia) toxic, croton protein (crassia), and croton-S) inhibitory protein (croton), and croton toxin (crassi) and derivatives thereof, Gelonin (gelonin), mitogellin (mitrellin) restrictocin (restricocin), phenomycin (phenomycin), enomycin (enomycin) and trichothecenes (trichothecenes).

The term "chemotherapeutic agent" is a compound that can be used to treat tumors. The definition also includes anti-hormonal agents that act to modulate, reduce, block or inhibit the effects of hormones that promote cancer growth, and are often in the form of systemic or systemic treatment. They may themselves be hormones. Examples of chemotherapeutic agents include alkylating agents, such as thiotepa; cyclophosphamide (CYTOXA)N ^TM) (ii) a Alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziridines (aziridines) such as benzodidopa (benaodopa), carboquone (carboquone), meltupipa (meturedopa) and uretonimine (uredopa); aziridine and methylmelamine including altretamine, triimipramine, triethylenephosphoramide, triethylenethiophosphoramide and trimethylolmelamine; nitrogen mustards (nitrogen mustards) such as chlorambucil, cholorfamide (cholorophosphamide), estramustine (estramustine), ifosfamide (ifosfamide), mechlorethamine (mechlorethamine), mechlorethamine hydrochloride; l-phenylalanine mustard (melphalan), neomustard (novembichin), cholesteryl phenylacetate mustard, prednimustine (prednimustine), trofosfamide (trofosfamide), uracil mustard; nitrosoureas (nitrosureas) such as nitrosourea mustard (carmustine), chlorozotocin (chlorozotocin), fotemustine (fotemustine), lomustine (lomustine), nimustine (nimustine), ramustine (ranimustine); antibiotics such as aclacinomycin, actinomycin, antromycin (authramycin), azaserine, bleomycin, actinomycin c (cactinomycin), calicheamicin (calicheamicin), carabacin, carminomycin (chromomycin), carzinophilin (carzinophilin), chromomycin, actinomycin D, daunorubicin (daunorubicin), ditobicin (detorubicin), 6-diazo-5-oxo-L-norleucine, doxorubicin (doxorubicin), epirubicin (epirubicin), esorubicin (esorubicin), idarubicin (idarubicin), marcellomycin (marcellomycin), mitomycin, mycophenolic acid, nogalamycin (nogalamycin), olivomycin (olivomycin), pelomycin (polypeomycin), polypeomycin, puromycin, polymyxin (griseofycin), streptomycin (roxithromycin); streptozotocin (streptozocin), tubercidin (tuberculin), ubenimex (ubenimex), azinostatin (zinostatin), zorubicin (zorubicin); antimetabolites such as methotrexate, 5-fluorouracil (5-FU); folic acid analogs such as denopterin, methotrexate, pteropterin, trimetrexate; pterine analogue fludarabine (f1udarabine), 6-mercaptopterin, thiaminePterin, thioguanopterin; pyrimidine analogs such as ancitabine (ancitabine), azacitidine (azacitidine), 6-azauridine, carmofur (carmofur), cytarabine, dideoxyuridine (doxitluridine), enocitabine (enocitabine), floxuridine, 5-FU; androgens such as dimethyltestosterone (calusterone), methyl androsterone propionate (dromostanolong propionate), epitioandrostanol (epitiostanol), mepiquat chloride (mepiquitane), and testolactone (testolactone); anti-adrenals such as aminoglutethimide (aminoglutethimide), mitotane (mitotane), trilostane (trilostane); folic acid supplements such as folinic acid (Frolinic acid); vinegar-processed gluconolactone; an aldophosphamide glycoside (aldophosphamideglycoside); aminolevulinic acid (aminolevulinic acid); amsacrine (amsacrine); bestrabuucil; bisantrene; edatrexate (edatraxate); defofamine; colchicine; diazaquinone (diaziqutone); elfosmithine; ammonium etitanium acetate; etoglut (etoglucid); gallium nitrate; a hydroxyurea; lentinan (lentinan); lonidamine (lonidamine); mitoguazone (mitoguzone); mitoxantrone (mitoxantrone); mopidamol (mopidamol); nifurthradine (nitracrine); pentostatin (pintostatin); phenamett; pirarubicin (pirarubicin); podophyllinic acid (podophyllinic acid); 2-ethyl hydrazide; procarbazine (procarbazine);

razoxane (rizoxane); sisofilan (sizofiran); germanium spiroamines (spirogyranium); alternarionic acid; a tri-imine quinone; 2, 2', 2 "-trichlorodiethylamine (trichlororrothriethylamine); urethane (urethan); vinca amides; dacarbazine (dacarbazine); mannitol mustard; dibromomannitol (mitobronitol); dibromodulcitol; a pipobroman pit (pipobroman); a polycytidysine; arabinoside ("Ara-C"); cyclophosphamide; thiotepa (thiotepa); taxanes, e.g. paclitaxel (A)

Bristol-Myers Squibb Oncology,Princeton, NJ) and docetaxel ((R)

Rhone-Poulenc Rorer, Antony, France); chlorambucil; gemcitabine (gemcitabine); 6-thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisplatin and carboplatin; vinblastine; platinum; etoposide (VP-16); an isocyclic phosphamidon glue; mitomycin C; mitoxantrone; vincristine; vinorelbine (vinorelbine); neomycin amide (navelbine); noxiatrone (novantrone); teniposide (teniposide); daunorubicin; aminopterin; (xiloda); ibandronate (ibandronate); CPT-11; topoisomerase inhibitor RFS 2000; difluoromethyl ornithine (DMFO); retinoic acid esperamicins; capecitabine (capecitabine); and pharmaceutically acceptable salts, acids or derivatives of any of the foregoing. This definition also includes anti-hormonal agents that modulate or inhibit the effects of hormones on tumors, such as anti-estrogen agents including tamoxifen (tamoxifen), raloxifene (raloxifene), the aromatase inhibitor 4(5) -imidazole, 4-hydroxyttamoxifen, trioxifene (trioxifene), raloxifene (keoxifene), LY117018, onapristone (onapristone), and toremifene (Fareston); and antiandrogen agents such as flutamide, nilutamide, bicalutamide, leuprolide and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the foregoing.

An "antibody" as described in the present disclosure refers to an immunoglobulin, a complete antibody being a tetrapeptide chain structure formed by two identical heavy chains and two identical light chains linked by interchain disulfide bonds. The constant regions of immunoglobulin heavy chains differ in their amino acid composition and arrangement, and thus, their antigenicity. Accordingly, immunoglobulins can be classified into five classes, otherwise known as the isotype of immunoglobulins, i.e., IgM, IgD, IgG, IgA, and IgE, with their corresponding heavy chains being the μ, δ, γ, α, and ε chains, respectively. The same class of igs can be divided into different subclasses according to differences in amino acid composition of the hinge region and the number and position of disulfide bonds in the heavy chain, and for example, iggs can be classified into IgG1, IgG2, IgG3 and IgG 4. Light chains are classified as either kappa or lambda chains by differences in the constant regions. Each of the five classes of Ig may have either a kappa chain or a lambda chain.

The sequences of the antibody heavy and light chains, near the N-terminus, are widely varied by about 110 amino acids, the variable region (Fv region); the remaining amino acid sequence near the C-terminus is relatively stable and is a constant region. The variable regions include 3 hypervariable regions (HVRs) and 4 Framework Regions (FRs) which are relatively sequence conserved. The 3 hypervariable regions determine the specificity of the antibody, also known as Complementarity Determining Regions (CDRs). Each of the light chain variable region (VL) and the heavy chain variable region (VH) is composed of 3 CDR regions and 4 FR regions, and the sequence from the amino terminus to the carboxyl terminus is: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR 4. The 3 CDR regions of the light chain refer to LCDR1, LCDR2, and LCDR 3; the 3 CDR regions of the heavy chain are referred to as HCDR1, HCDR2 and HCDR 3.

Antibodies of the present disclosure include murine, chimeric, and humanized antibodies.

The term "murine antibody" is in the present disclosure a monoclonal antibody against human claudin18.2 prepared according to the knowledge and skill in the art. The preparation is carried out by injecting the test subject with Claudin18.2 or an epitope thereof as an antigen and then isolating hybridomas expressing antibodies having the desired sequence or functional properties. In a preferred embodiment of the present disclosure, the murine anti-claudin 18.2 antibody, or antigen binding fragment thereof, may further comprise a light chain constant region of a murine kappa, lambda chain or variant thereof, or further comprise a heavy chain constant region of a murine IgG1, IgG2, IgG3 or variant thereof.

The term "chimeric antibody" refers to an antibody obtained by fusing a variable region of a murine antibody to a constant region of a human antibody, and can reduce an immune response induced by the murine antibody. Establishing chimeric antibody, firstly establishing hybridoma secreting mouse-derived specific monoclonal antibody, then cloning variable region gene from mouse hybridoma cell, cloning constant region gene of human antibody according to the need, connecting mouse variable region gene and human constant region gene into chimeric gene, inserting into expression vector, and finally expressing chimeric antibody molecule in eukaryotic system or prokaryotic system. In a preferred embodiment of the present disclosure, the antibody light chain of the chimeric antibody further comprises a light chain constant region of a human kappa, lambda chain or a variant thereof. The antibody heavy chain of the Claudin18.2 chimeric antibody further comprises a heavy chain constant region of human IgG1, IgG2, IgG3, IgG4 or variants thereof, preferably human IgG1, IgG2 or IgG4 heavy chain constant regions, or IgG1, IgG2 or IgG4 variants using amino acid mutations (e.g., L234A and/or L235A mutations, and/or S228P mutations).

The term "humanized antibody", also known as CDR-grafted antibody (CDR-grafted antibody), refers to an antibody produced by grafting CDR sequences of a non-human species into a human antibody variable region framework, i.e., a different type of human germline antibody framework sequence. Can overcome the heterogenous reaction induced by the chimeric antibody carrying a large amount of heterogenous protein components. Such framework sequences can be obtained from public DNA databases or published references that include germline antibody gene sequences. Germline DNA Sequences of genes such as the human heavy and light chain variable regions can be found in the "VBase" human germline sequence database (available on the Internet www.mrccpe.com.ac.uk/VBase), as well as in Kabat, E.A. et al, 1991Sequences of Proteins of Immunological Interest, 5 th edition. To avoid reduced immunogenicity and reduced activity, the human antibody variable region framework sequences may be minimally back-mutated or back-mutated to retain activity. The humanized antibodies of the present disclosure also include humanized antibodies after further affinity maturation mutagenesis of the CDRs by yeast display.

In one embodiment of the present disclosure, the antibody or antigen binding fragment thereof may further comprise a light chain constant region of a kappa, lambda chain of human or murine origin or a variant thereof, or further comprise a heavy chain constant region of IgG1, IgG2, IgG3, IgG4 or a variant thereof of human or murine origin; preferably comprising a human IgG1, IgG2 or IgG4 heavy chain constant region, or an IgG1, IgG2 or IgG4 variant using amino acid mutations (e.g., L234A and/or L235A mutations, and/or S228P mutations).

The "variants" of the heavy chain constant region of a human antibody and the light chain constant region of a human antibody in the present disclosure refer to variants of the heavy chain constant region or the light chain constant region of human origin that do not alter the structure and function of the antibody variable region, as disclosed in the prior art. Exemplary variants include IgG1, IgG2, IgG3, or IgG4 heavy chain constant region variants with site-directed engineering and amino acid substitutions to the heavy chain constant region; specific substitutions are YTE mutations, L234A and/or L235A mutations, S228P mutations, and/or mutations that gain the knob-into-hole structure (giving the antibody heavy chain a knob-Fc and hole-Fc combination) as known in the art, which have been shown to confer new properties to the antibody without altering the function of the antibody variable regions.

"human antibodies" (HuMAb), "humanized antibodies," "fully human antibodies" are used interchangeably and can be either human derived antibodies or antibodies obtained from a transgenic organism that is "engineered" to produce specific human antibodies in response to antigenic stimuli and can be produced by any method known in the art. In certain techniques, human heavy and light chain locus elements are introduced into cell lines derived from embryonic stem cell lines in which the endogenous heavy and light chain loci are targeted for disruption. Transgenic organisms can synthesize human antibodies specific for human antigens, and the organisms can be used to produce hybridomas that secrete human antibodies. A human antibody can also be an antibody in which the heavy and light chains are encoded by nucleotide sequences derived from one or more human DNA sources. Fully human antibodies can also be constructed by gene or chromosome transfection methods as well as phage display techniques, or by in vitro activated B cells, all of which are known in the art.

The terms "full-length antibody," "intact antibody," "complete antibody," and "whole antibody" are used interchangeably herein to refer to a substantially intact form of an antibody, as distinguished from antigen-binding fragments defined below. The term particularly refers to antibodies comprising constant regions in the light and heavy chains. The present disclosure "antibody" includes "full-length antibodies" and antigen-binding fragments thereof.

In some embodiments, the full length antibodies of the present disclosure include full length antibodies formed after the light chain variable regions and the light chain constant regions in the light and heavy chain variable region combinations in the table below are linked. Those skilled in the art can select different antibody-derived light chain constant regions and heavy chain constant regions, such as human antibody-derived light chain constant regions and heavy chain constant regions, according to actual needs.

The term "antigen-binding fragment" or "functional fragment" of an antibody refers to one or more fragments that retain the ability to specifically bind an antigen (e.g., claudin 18.2). It has been shown that fragments of full-length antibodies can be used to perform the antigen-binding function of the antibody. Examples of binding fragments encompassed within the term "antigen-binding fragment" of an antibody include (i) Fab fragments, monovalent fragments consisting of the VL, VH, CL and CH1 domains; (ii) f (ab')₂A fragment, a bivalent fragment comprising two Fab fragments connected by a disulfide bridge at the hinge region, (iii) an Fd fragment consisting of the VH and CH1 domains; (iv) (ii) an Fv fragment consisting of the VH and VL domains of a single arm of an antibody; (v) dsFv, antigen binding fragments formed by interchain disulfide bonds of VH and VL; (vi) diabodies, bispecific antibodies and multispecific antibodies comprising fragments of scFv, dsFv, Fab and the like. Furthermore, although the two domains of the Fv fragment, VL and VH, are linked by a synthetic linker, which enables them to be generated as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single chain Fv (scFv); see, e.g., Bird et al (1988) Science242: 423-. Such single chain antibodies are also included in the term "antigen-binding fragment" of an antibody. Such antibody fragments are obtained using conventional techniques known to those skilled in the art, and the fragments are screened for utility in the same manner as for intact antibodies. Antigen binding portions can be produced by recombinant DNA techniques or by enzymatic or chemical cleavage of intact immunoglobulins. The antibody may be of a different isotype, for example, an IgG (e.g., IgG1, IgG2, IgG3, or IgG4 subtype), IgA1, IgA2, IgD, IgE, or IgM antibody.

Fab is an antibody fragment having antigen binding activity among fragments obtained by treating an IgG antibody molecule with an enzyme having the same activity as papain.

F(ab') ₂Is obtained by digesting IgG with enzyme having the same activity as that of pepsinA binding-active antibody fragment.

Fab 'is obtained by cleaving the above-mentioned F (ab')₂And the obtained antibody fragment having an antigen-binding activity.

In addition, the Fab 'may be produced by inserting DNA encoding the Fab' fragment into an expression vector and introducing the vector into a host.

The term "single chain antibody", "single chain Fv" or "scFv" means a molecule comprising an antibody heavy chain variable domain (or region; VH) and an antibody light chain variable domain (or region; VL) joined by a linker. Such scFv molecules can have the general structure: NH (NH)₂-VL-linker-VH-COOH or NH₂-VH-linker-VL-COOH. Other linkers useful in the present disclosure are described by, for example, but not limited to: holliger et al (1993) Proc.Natl.Acad.Sci.USA 90: 6444-; alfthan et al (1995), Protein Eng.8: 725-731; choi et al (2001), Eur.J. Immuno l.31: 94-106; hu et al (1996), Cancer Res.56: 3055-3061; kipriyanov et al (1999), J.mol.biol.293:41-56 and Rovers et al (2001), Cancer immunol.

Diabodies are antibody fragments in which the scFv or Fab is dimerized, and are antibody fragments having bivalent antigen binding activity. In the divalent antigen binding activity, the two antigens may be the same or different.

Bispecific antibodies and multispecific antibodies refer to antibodies that are capable of binding two or more antigens or antigenic determinants.

The dsFv is obtained by linking a polypeptide in which one amino acid residue in each of VH and VL is substituted with a cysteine residue via a disulfide bond between cysteine residues. Amino acid residues substituted with cysteine residues can be selected based on the prediction of the three-dimensional structure of the antibody according to known methods (e.g., Protein Engineering, 7, 697 (1994)).

The term "amino acid difference" or "amino acid mutation" refers to the presence of amino acid changes or mutations in a variant protein or polypeptide as compared to the original protein or polypeptide, including 1, 2, 3, or more amino acid insertions, deletions, or substitutions based on the original protein or polypeptide.

The term "antibody framework" or "FR region" refers to a portion of a variable domain VL or VH that serves as a scaffold for the antigen binding loops (CDRs) of that variable domain. It is essentially a variable domain without CDRs.

The term "complementarity determining region", "CDR" or "hypervariable region" refers to one of the 6 hypervariable regions within the variable domain of an antibody which primarily contributes to antigen binding. Typically, there are three CDRs (HCDR1, HCDR2, HCDR3) per heavy chain variable region and three CDRs (LCDR1, LCDR2, LCDR3) per light chain variable region. The amino acid sequence boundaries of the CDRs may be determined using any of a variety of well known protocols, including the "Kabat" numbering convention (see Kabat et Al (1991), "Sequences of Proteins of Immunological Interest", 5 th edition, Public Health Service, National Institutes of Health, Bethesda, MD), "Chothia" numbering convention (see Al-Lazikani et Al, (1997) JMB 273: 927-948) and ImMunogenetics IMGT (Lefranc M.P., immunogist, 7, 132-136 (1999); Lefranc, M.P. et Al, Dev.Comp.27, 55-77(2003), (2003) et Al, for example, following the classical Kabat numbering convention, the amino acid sequence boundaries in the variable domain (VH) are residues 35-31), the CDR 35-34 (VH) and CDR 35-34 (CDR 54), the light chain numbering convention (LCDR 3675-3650) (35-2) and the LCDR 2-34 (35-11) CDR 75 (35-3) and the LCDR2 (35-3) CDR 75 (35-3) residues in the variable domain (LCDR2), CDR amino acid numbers in VH were 26-32(HCDR1), 52-56(HCDR2) and 95-102(HCDR 3); and amino acid residues in VL are numbered 26-32(LCDR1), 50-52(LCDR2) and 91-96(LCDR 3). By combining the CDR definitions of both Kabat and Chothia, the CDRs are made up of amino acid residues 26-35(HCDR1), 50-65(HCDR2) and 95-102(HCDR3) in the human VH and amino acid residues 24-34(LCDR1), 50-56(LCDR2) and 89-97(LCDR3) in the human VL. Following the rules of IMGT, the CDR amino acid residue numbers in VH are approximately 26-35(CDR1), 51-57(CDR2) and 93-102(CDR3), and the CDR amino acid residue numbers in VL are approximately 27-32(CDR1), 50-52(CDR2) and 89-97(CDR 3). Following the IMGT rules, the CDR regions of the antibody can be determined using the program IMGT/DomainGap Align.

The term "epitope" or "antigenic determinant" refers to a site on an antigen to which an immunoglobulin or antibody binds (e.g., a specific site on the claudin18.2 molecule). Epitopes typically comprise at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 contiguous or non-contiguous amino acids in a unique spatial conformation. See, e.g., epipope Mapping Protocols in Methods in Molecular B biology, volume 66, g.e. morris, Ed. (1996).

The terms "specific binding," "selective binding," "selectively binds," and "specifically binds" refer to the binding of an antibody to an epitope on a predetermined antigen. Typically, the antibody is administered at a rate of about less than 10^-8M, e.g. less than about 10^-9M、10 ^-10M、10 ^-11M、10 ^-12M or less affinity (KD) binding.

The term "KD" refers to the dissociation equilibrium constant of a particular antibody-antigen interaction. Typically, the antibodies of the present disclosure are administered at less than about 10^-7M, e.g. less than about 10^-8M or 10^-9The dissociation equilibrium constant (KD) of M binds to claudin18.2 or an epitope thereof, e.g., in the present disclosure affinity of an antibody to a cell surface antigen is determined by FACS.

The term "compete" when used in the context of antigen binding proteins that compete for the same epitope means competition between antigen binding proteins, as determined by the following assay: in the assay, the antigen binding protein to be detected (e.g., an antibody or functional fragment thereof) prevents or inhibits (e.g., reduces) specific binding of a reference antigen binding protein (e.g., a ligand or a reference antibody) to a common antigen (e.g., the claudin18.2 antigen or fragment thereof). Numerous types of competitive binding assays are available for determining whether an antigen binding protein competes with another, such as: solid phase direct or indirect Radioimmunoassays (RIA), solid phase direct or indirect Enzyme Immunoassays (EIA), sandwich competition assays (see, e.g., Stahli et al, 1983, methods in Enzymology 9: 242-; solid phase direct biotin-avidin EIA (see, e.g., Kirkland et al, 1986, J.Immunol.137: 3614-), solid phase direct labeling assay, solid phase direct labeling sandwich assay (see, e.g., Harlow and Lane, 1988, Antibodies, A Laboratory Manual, Cold Spring Harbor Press); direct labeling of RIA with a solid phase of I-125 label (see, e.g., Morel et al, 1988, mol. Immunol.25: 7-15); solid phase direct biotin-avidin EIA (see, e.g., Cheung, et al, 1990, Virology 176: 546-552); and directly labeled RIA (Moldenhauer et al, 1990, Scand. J. Immunol.32: 77-82). Typically, the assay involves the use of purified antigen bound to a solid surface or cell bearing either an unlabeled test antigen binding protein or a labeled reference antigen binding protein. Competitive inhibition is measured by measuring the amount of label bound to a solid surface or cell in the presence of the antigen binding protein being measured. Typically the antigen binding protein to be detected is present in excess. Antigen binding proteins identified by competitive assays (competing antigen binding proteins) include: an antigen binding protein that binds to the same epitope as a reference antigen binding protein; and an antigen binding protein that binds a contiguous epitope sufficiently close to the binding epitope of the reference antigen binding protein that the two epitopes sterically hinder binding from occurring. Additional details regarding methods for determining competitive binding are provided in the examples herein. Typically, when a competing antigen binding protein is present in excess, it will inhibit (e.g., decrease) the specific binding of at least 40-45%, 45-50%, 50-55%, 55-60%, 60-65%, 65-70%, 70-75%, or 75% or more of a reference antigen binding protein to a common antigen. In certain instances, binding is inhibited by at least 80-85%, 85-90%, 90-95%, 95-97%, or 97% or more.

The term "nucleic acid molecule" as used herein refers to both DNA molecules and RNA molecules. The nucleic acid molecule may be single-stranded or double-stranded, preferably double-stranded DNA or single-stranded mRNA or modified mRNA. A nucleic acid is "operably linked" when it is placed into a functional relationship with another nucleic acid sequence. For example, a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the coding sequence.

Amino acid sequence "identity" refers to the percentage of amino acid residues in a first sequence that are identical to the amino acid residues in a second sequence when the amino acid sequences are aligned (gaps are introduced if necessary) to achieve the maximum percent sequence identity, and without considering any conservative substitutions as part of the sequence identity. To determine percent amino acid sequence identity, an alignment can be achieved in a variety of ways that are within the skill in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN-2, or Megalign (DNASTAR) software. One skilled in the art can determine parameters suitable for measuring alignment, including any algorithms required to achieve maximum alignment over the full length of the sequences being compared.

The term "expression vector" refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. In one embodiment, the vector is a "plasmid," which refers to a circular double-stranded DNA loop into which additional DNA segments can be ligated. In another embodiment, the vector is a viral vector, wherein additional DNA segments may be ligated into the viral genome. The vectors disclosed herein are capable of autonomous replication in a host cell into which they have been introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors) or can be integrated into the genome of a host cell upon introduction into the host cell so as to be replicated along with the host genome (e.g., non-episomal mammalian vectors).

Methods for producing and purifying antibodies and antigen-binding fragments are well known in the art, such as the Cold spring harbor antibody protocols, chapters 5-8 and 15. For example, mice can be immunized with human Claudin18.2 or fragments thereof, and the resulting antibodies can be renatured, purified, and amino acid sequenced using conventional methods. Antigen-binding fragments can likewise be prepared by conventional methods. The antibody or antigen binding fragment of the invention is genetically engineered to add one or more human FR regions to the CDR regions of non-human origin. Human FR germline sequences can be obtained from the website http:// IMGT. cities.fr of ImmunoGeneTiCs (IMGT) or from the immunoglobulin journal, 2001ISBN012441351, by aligning the IMGT human antibody variable region germline gene database with the MOE software.

The term "host cell" refers to a cell into which an expression vector has been introduced. Host cells may include bacterial, microbial, plant or animal cells. Bacteria susceptible to transformation include members of the enterobacteriaceae family (enterobacteriaceae), such as strains of Escherichia coli (Escherichia coli) or Salmonella (Salmonella); bacillaceae (Bacillus) such as Bacillus subtilis; pneumococcus (Pneumococcus); streptococcus (Streptococcus) and Haemophilus influenzae (Haemophilus influenzae). Suitable microorganisms include Saccharomyces cerevisiae and Pichia pastoris. Suitable animal host cell lines include CHO (chinese hamster ovary cell line), 293 cells and NS0 cells.

The antibodies or antigen-binding fragments of the present disclosure can be prepared and purified using conventional methods. For example, cDNA sequences encoding the heavy and light chains may be cloned and recombined into an expression vector. Recombinant immunoglobulin expression vectors can stably transfect host cells. As a more recommended prior art, mammalian expression systems result in glycosylation of antibodies, particularly at the highly conserved N-terminal site of the Fc region. Stable clones were obtained by expression of antibodies that specifically bind to human Claudin18.2. Positive clones were expanded in a bioreactor to produce antibodies. The antibody-secreting culture medium can be purified by conventional techniques. For example, purification is carried out using an A or G Sepharose FF column containing a buffer adjusted. Non-specifically bound fractions are washed away. And eluting the bound antibody by using a pH gradient method, detecting the antibody fragment by using SDS-PAGE, and collecting. The antibody can be concentrated by filtration by a conventional method. Soluble mixtures and polymers can also be removed by conventional methods, such as molecular sieves, ion exchange. The resulting product is either immediately frozen, e.g., -70 ℃, or lyophilized.

"administration," "administering," and "treating," when applied to an animal, human, experimental subject, cell, tissue, organ, or biological fluid, refers to contact of an exogenous drug, therapeutic agent, diagnostic agent, or composition with the animal, human, subject, cell, tissue, organ, or biological fluid. "administration," "administering," and "treating" may refer to, for example, therapeutic, pharmacokinetic, diagnostic, research, and experimental methods. The treatment of the cells comprises contacting the reagent with the cells and contacting the reagent with a fluid, wherein the fluid is in contact with the cells. "administering", "administering" and "treating" also mean treating, for example, a cell in vitro and ex vivo by an agent, a diagnostic, a binding composition, or by another cell. "treatment" when applied to a human, veterinary or research subject refers to therapeutic treatment, prophylactic or preventative measures, research and diagnostic applications.

By "treating" is meant administering a therapeutic agent, e.g., a composition comprising any one of the antibodies or antigen-binding fragments of the disclosure, either internally or externally to a patient having one or more disease symptoms for which the therapeutic agent is known to have a therapeutic effect. Typically, the therapeutic agent is administered in the subject patient or population in an amount effective to alleviate one or more symptoms of the disease, to induce regression of such symptoms or to inhibit development of such symptoms to any clinically useful degree. The amount of therapeutic agent effective to alleviate any particular disease symptom (also referred to as a "therapeutically effective amount") can vary depending on a variety of factors, such as the disease state, age, and weight of the patient, and the ability of the drug to produce a desired therapeutic effect in the patient. Whether a disease symptom has been reduced can be assessed by any clinical test commonly used by physicians or other health professional to assess the severity or progression of the symptom. Although embodiments of the present disclosure (e.g., methods of treatment or articles of manufacture) may be ineffective in alleviating the symptoms of each target disease, they should alleviate the symptoms of the target disease in a statistically significant number of patients as determined according to any statistical test method known in the art, such as Student's t-test, chi-square test, U-test by Mann and Whitney, Kruskal-Wallis test (H-test), Jonckhere-Terpstra test, and Wilcoxon test.

"conservative modification" or "conservative substitution" refers to the replacement of an amino acid in a protein with another amino acid having similar characteristics (e.g., charge, side chain size, hydrophobicity/hydrophilicity, backbone conformation, and rigidity, etc.) so that changes can be made frequently without changing the biological activity of the protein. It is known to The person skilled in The art that, in general, a single amino acid substitution in a non-essential region of a polypeptide does not substantially alter The biological activity (see, for example, Watson et al (1987) Molecular Biology of The Gene, The Benjamin/Cummings pub. Co., p. 224, (4 th edition)). In addition, substitution of structurally or functionally similar amino acids is unlikely to abolish biological activity. Exemplary conservative substitutions are set forth in the following table "exemplary amino acid conservative substitutions".

TABLE 3 exemplary amino acid conservative substitutions

Original residues	Conservative substitutions
Ala(A)	Gly；Ser
Arg(R)	Lys；His
Asn(N)	Gln；His；Asp
Asp(D)	Glu；Asn
Cys(C)	Ser；Ala；Val
Gln(Q)	Asn；Glu
Glu(E)	Asp；Gln
Gly(G)	Ala
His(H)	Asn；Gln

Ile(I)	Leu；Val
Leu(L)	Ile；Val
Lys(K)	Arg；His
Met(M)	Leu；Ile；Tyr
Phe(F)	Tyr；Met；Leu
Pro(P)	Ala
Ser(S)	Thr
Thr(T)	Ser
Trp(W)	Tyr；Phe
Tyr(Y)	Trp；Phe
Val(V)	Ile；Leu

An "effective amount" or "effective dose" refers to the amount of a drug, compound or pharmaceutical composition necessary to achieve any one or more beneficial or desired therapeutic results. For prophylactic use, beneficial or desired results include elimination or reduction of risk, lessening severity, or delaying onset of the condition, including biochemical, histological, and/or behavioral symptoms of the condition, its complications, and intermediate pathological phenotypes exhibited during development of the condition. For therapeutic applications, beneficial or desired results include clinical results, such as reducing the incidence of or ameliorating one or more symptoms of various target antigen-associated disorders of the disclosure, reducing the dosage of other agents required to treat the disorder, enhancing the therapeutic efficacy of another agent, and/or delaying the progression of a target antigen-associated disorder of the disclosure in a patient.

"exogenous" refers to a substance produced outside an organism, cell or human body as the case may be.

"endogenous" refers to a substance produced in a cell, organism, or human body as the case may be.

"identity" refers to sequence similarity between two polynucleotide sequences or between two polypeptides. When a position in both of the two compared sequences is occupied by the same base or amino acid monomer subunit, e.g., if each position of two DNA molecules is occupied by adenine, then the molecules are homologous at that position. The percent identity between two sequences is a function of the number of matching or homologous positions common to both sequences divided by the number of positions compared x 100. For example, two sequences are 60% homologous if there are 6 matches or homologies at 10 positions in the two sequences when the sequences are optimally aligned; two sequences are 95% homologous if there are 95 matches or homologies at 100 positions in the two sequences. Typically, comparisons are made when aligning two sequences to give the maximum percent identity. For example, the comparison may be performed by the BLAST algorithm, wherein the parameters of the algorithm are selected to give the maximum match between the respective sequences over the entire length of the respective reference sequences. The following references refer to the BLAST algorithm often used for sequence analysis: BLAST algorithm (BLAST ALGORITHMS) Altschul, S.F. et al, (1990) J.mol.biol.215: 403-; gish, W. et al, (1993) Nature Genet.3: 266-; madden, T.L. et al, (1996) meth.Enzymol.266: 131-; altschul, S.F. et al, (1997) Nucleic Acids Res.25: 3389-3402; zhang, J. et al, (1997) Genome Res.7: 649-. Other conventional BLAST algorithms, such as provided by NCBI BLAST, are also well known to those skilled in the art.

As used herein, the expressions "cell," "cell line," and "cell culture" are used interchangeably, and all such designations include progeny. Thus, "transformants" and "transformed cells" include the primary test cell and cultures derived therefrom, regardless of the number of passages. It is also understood that all progeny may not be precisely identical in DNA content due to deliberate or inadvertent mutations. Mutant progeny that have the same function or biological activity as screened for in the originally transformed cell are included. Where different names are intended, they are clearly visible from the context.

By "isolated" is meant a molecule that is substantially free of other biomolecules, such as nucleic acids, proteins, lipids, carbohydrates, or other materials, such as cell debris and growth media. Generally, the term "isolated" is not intended to refer to the complete absence of such materials or the absence of water, buffers, or salts, unless they are present in amounts that significantly interfere with the experimental or therapeutic use of the compounds as described herein.

"optional" or "optionally" means that the subsequently described event or circumstance may, but need not, occur, and that the description includes instances where the event or circumstance occurs or does not.

"pharmaceutical composition" means a mixture containing one or more compounds described herein or a physiologically/pharmaceutically acceptable salt or prodrug thereof and other chemical components, such as physiologically/pharmaceutically acceptable carriers and excipients. The purpose of the pharmaceutical composition is to facilitate administration to an organism, facilitate absorption of the active ingredient and exert biological activity.

The term "pharmaceutically acceptable carrier" refers to any inactive substance suitable for use in formulations for delivery of the antibody or antigen-binding fragment. The carrier may be an anti-adherent, binder, coating, disintegrant, filler or diluent, preservative (e.g., antioxidant, antibacterial or antifungal agent), sweetener, absorption retarder, wetting agent, emulsifier, buffer, or the like. Examples of suitable pharmaceutically acceptable carriers include water, ethanol, polyols (e.g., glycerol, propylene glycol, polyethylene glycol, and the like) dextrose, vegetable oils (e.g., olive oil), saline, buffers, buffered saline, and isotonic agents such as sugars, polyols, sorbitol, and sodium chloride.

Further, the present disclosure includes an agent for treating a disease associated with an antigen of interest (e.g., claudin18.2) positive cell, comprising as an active ingredient an anti-claudin 18.2 antibody or antigen binding fragment thereof of the present disclosure.

The disease associated with claudin18.2 in the present disclosure is not limited as long as it is a disease associated with claudin18.2, for example, the molecular induced therapeutic response of the present disclosure includes: (1) repressing binding of claudin18.2 to its receptor/ligand by binding to human claudin18.2, or (2) killing tumor cells that overexpress claudin 18.2. Thus, the molecules of the present disclosure are very useful, when in preparations and formulations suitable for therapeutic applications, for those people who have tumors or cancers, preferably melanoma, colon cancer, breast cancer, lung cancer, stomach cancer, intestinal cancer, kidney cancer, non-small cell lung cancer, bladder cancer, and the like.

Further, the present disclosure relates to a method for immunodetection or assay of a target antigen (e.g., claudin18.2), a reagent for immunodetection or assay of a target antigen (e.g., claudin18.2), a method for immunodetection or assay of a cell expressing a target antigen (e.g., claudin18.2), and a diagnostic agent for diagnosis of a disease associated with a target antigen (e.g., claudin18.2) positive cell, which comprises, as an active ingredient, an antibody or an antibody fragment of the present disclosure that specifically recognizes a target antigen (e.g., human claudin18.2) and binds to an amino acid sequence of an extracellular region or a three-dimensional structure thereof.

In the present disclosure, the method for detecting or determining the amount of the antigen of interest (e.g., claudin18.2) can be any known method. For example, it includes immunodetection or assay methods.

The immunoassay or measuring method is a method for detecting or measuring the amount of an antibody or the amount of an antigen using a labeled antigen or antibody. Examples of the immunological detection or measurement method include a radioactive substance-labeled immune antibody method (RIA), an enzyme immunoassay (EIA or ELISA), a Fluorescence Immunoassay (FIA), a luminescence immunoassay, a western immunoblotting method, a physicochemical method, and the like.

The above-mentioned diseases associated with claudin18.2 positive cells can be diagnosed by detecting or assaying cells expressing claudin18.2 with the antibodies or antibody fragments of the present disclosure.

For detecting cells expressing the polypeptide, a known immunoassay method can be used, and immunoprecipitation, fluorescent cell staining, immunohistological staining, or the like is preferably used. In addition, a fluorescent antibody staining method using FMAT8100HTS system (Applied Biosystem) or the like can be used.

In the present disclosure, the sample to be tested for detecting or measuring the target antigen (e.g., claudin18.2) is not particularly limited as long as it has a possibility of containing cells expressing the target antigen (e.g., claudin18.2), such as tissue cells, blood, plasma, serum, pancreatic juice, urine, feces, tissue fluid, or culture fluid.

The diagnostic agent containing the monoclonal antibody or antibody fragment thereof of the present disclosure may further contain a reagent for performing an antigen-antibody reaction or a reagent for detecting a reaction, depending on the desired diagnostic method. Reagents for performing antigen-antibody reactions include buffers, salts, and the like. The reagent for detection includes reagents generally used in immunodetection or assay methods, such as a labeled secondary antibody recognizing the monoclonal antibody, an antibody fragment thereof or a binding substance thereof, a substrate corresponding to the label, and the like.

The details of one or more embodiments of the invention are set forth in the description above. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims. In the specification and claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All patents and publications cited in the specification are herein incorporated by reference. The following examples are set forth in order to more fully illustrate the preferred embodiments of the present invention. These examples should not be construed in any way to limit the scope of the invention, which is defined in the claims.

Examples

Example 1: construction of cell line highly expressing Claudin18.2

Transfecting the pCDH-hClaudin18.2 lentivirus expression vector plasmid and a pVSV-G, pCMV-dR8.91 lentivirus system packaging vector into a virus packaging cell 293T by using a Lipofectamine 3000 transfection reagent; collecting culture medium supernatant containing virus, filtering and centrifuging at ultra high speed; infecting human gastric signet ring cell cancer cell strain NUGC4 with the concentrated virus, screening by puromycin for two to three weeks, and performing FACS single cell sorting.

The degree of claudin18.2 expression was differentiated according to the tumor IHC score. Cells with expression levels equivalent to the expression level of tumor Claudin18.2 with a tumor IHC score of 3 points are high expressing cells, and cells with expression levels equivalent to the expression level of tumor Claudin18.2 with a tumor IHC score of 2 points are medium expressing cells. According to the detection of Claudin18.2 expression on the cell surface of the lentivirus-infected NUGC4 cell by FACS, a single clone cell strain NUGC4/hClaudin18.2 with high Claudin18.2 expression level is selected. Meanwhile, the expression of Claudin18.2 on the surface of a wild-type NUGC4 cell is detected by FACS, a NUGC4 clone cell strain with medium expression level of Claudin18.2 is selected, and the wild-type NUGC4 is a cell with low expression level of Claudin18.2.

The selected monoclonal cell lines were expanded and frozen for storage in a stock for subsequent experiments.

Claudin18.2 sequence Genbank NP-001002026: (SEQ ID NO:1)

Claudin18.2dna sequence: (SEQ ID NO:2)

Example 2: anti-human claudin18.2 monoclonal antibody production

1 immunization

Anti-human Claudin18.2 monoclonal antibodies were generated by immunizing mice.

The experimental SJL white mice, female, 6-8 weeks old (Beijing Witongliwa laboratory animal technology, Inc., animal production license number: SCXK (Jing) 2012-0001). A breeding environment: SPF grade. After the mice are purchased, the mice are raised in a laboratory environment for 1 week, and the light/dark period is regulated for 12/12 hours at the temperature of 20-25 ℃; the humidity is 40-60%. Mice that had been acclimatized were immunized according to the following protocol. The immune antigen is huClaudin18.2-HEK293 cells (HEK-293 stable cell strain transfected with human Claudin18.2 plasmid).

Immunization protocol: before the first immunization of cells, use

Gold Adjuvant (Sigma Cat No. t2684)0.1 ml/mouse injected Intraperitoneally (IP); half an hour later, each mouse was diluted to 1X 10 by Intraperitoneal (IP) injection of 0.1ml of physiological saline⁸Cell sap at a concentration of/ml. The inoculation is carried out after the cells are blown evenly,the time periods were 0, 14, 28, 42, and 56 days. Blood was collected on days 21, 35, 49 and 63, and the antibody titer in mouse serum was determined by ELISA. After 4-5 immunizations, mice with high antibody titers in serum and titers tending to plateau were selected for splenocyte fusion. Boosting 3 days before splenocyte fusion, Intraperitoneal (IP) injection of 1X 10⁷A cell.

2 spleen cell fusion

Spleen lymphocytes and myeloma cells Sp2/0 cells by PEG-mediated fusion step (

CRL-8287 ^TM) And carrying out fusion to obtain hybridoma cells. The hybridoma cell size is 0.5-1 × 10⁶The density of each ml was resuspended in complete medium (IMDM medium containing 20% FBS, 1 XHAT, 1 XPPI), 100. mu.l/well in 96-well plates, 37 ℃, 5% CO₂After 3-4 days of incubation, 100. mu.l/well of HAT complete medium was supplemented, and culture was continued for 3-4 days until colonies were formed. The supernatant was removed and 200. mu.l/well of HT complete medium (IMDM medium with 20% FBS, 1 XHT and 1 XPI) was added at 37 ℃ with 5% CO₂ELISA was performed after 3 days of culture.

3 hybridoma cell selection

The culture supernatants were assayed by a combination of ELISA methods based on the density of hybridoma cell growth. Selecting cells which have strong binding capacity with huClaudin18.2-HEK293 cells and are not bound with the HEK293 cells, and performing amplification and cryopreservation in time; two to three subclones were performed until single cell clones were obtained.

Cell binding experiments were performed for each subcloned cell. Hybridoma clones were obtained by screening in the above experiment, and further antibody was prepared by serum-free cell culture method, and purified according to the purification examples for use in the detection examples.

Example 3: humanization of murine antibodies

Selecting monoclonal hybridoma cell strains mAb1901 and mAb1902 with high in vitro activity; the monoclonal antibody sequence was cloned and then humanized, recombinant expression and activity evaluation was performed.

The process of cloning sequences from hybridomas is as follows. The logarithmic growth phase hybridoma cells were harvested, RNA extracted using Trizol (Invitrogen,15596-018) (according to the kit instructions) and reverse transcribed (PrimeScript)^TMReverse Transcriptase, Takara, cat # 2680A). The cDNA obtained by reverse transcription was amplified by PCR using mouse Ig-Primer Set (Novagen, TB326Rev.B 0503) and sequenced by sequencer. The amino acid sequence corresponding to the obtained DNA sequence is shown as SEQ ID NO 3-6:

mAb1901 murine heavy chain variable region (SEQ ID NO:3)

mAb1901 murine light chain variable region (SEQ ID NO:4)

mAb1902 murine heavy chain variable region (SEQ ID NO:5)

mAb1902 murine light chain variable region (SEQ ID NO:6)

The murine heavy chain variable region and the murine light chain variable region were linked to the heavy chain constant region and the human kappa light chain constant region of the following human IgG1 antibody, respectively, to form chimeric antibodies ch1901 and ch 1902.

The constant region is selected from the following sequences:

heavy chain constant region of human IgG1 antibody: (SEQ ID NO:7)

Human kappa light chain constant region: (SEQ ID NO:8)

Monoclonal antibodies of murine origin are humanized as described in many publications in the art. Briefly, human germline antibody sequences are selected for CDR grafting based on the homology of the murine and human antibodies using human constant domains instead of the parent (murine antibody) constant domains. The present invention selects a candidate molecule having a good activity for humanization, and the results are as follows.

1. CDR regions of murine antibodies

The amino acid residues of the VH/VL CDRs in Table 4 were determined and annotated by the Kabat numbering system.

The CDR sequences of the murine antibodies are shown in table 4:

TABLE 4 CDR sequences of murine antibodies

Antibodies	mAb1901
HCDR1	DYGIH(SEQ ID NO:9)
HCDR2	YISRGSSTIYYADTVKG(SEQ ID NO:10)
HCDR3	GGYDTRNAMDY(SEQ ID NO:11)
LCDR1	KSSQSLLNSGNQKNYLA(SEQ ID NO:12)
LCDR2	GASTRAS(SEQ ID NO:13)
LCDR3	QNDLYYPLT(SEQ ID NO:14)
Antibodies	mAb1902
HCDR1	SYWMH(SEQ ID NO:15)
HCDR2	MIHPNSGSTNYNEKFKGR(SEQ ID NO:16)
HCDR3	LKTGNSFDY(SEQ ID NO:17)
LCDR1	KSSQSLLNSGNQKNYLT(SEQ ID NO:18)
LCDR2	WASTRES(SEQ ID NO:19)
LCDR3	QNAYTYPFT(SEQ ID NO:20)

2. Selection of human germline FR region sequences

On the basis of the obtained typical structure of the mouse antibody VH/VLCDR, the heavy chain variable region sequence and the light chain variable region sequence are compared with an antibody Germline database to obtain a human Germline template with high homology. Wherein the human germline light chain framework region is from a human kappa light chain gene.

2.1 humanization and Back-mutation design of mAb1901

Selecting a proper human antibody germ line, carrying out humanized transformation on the mAb1901 murine antibody, and transplanting the CDR region of the murine antibody mAb1901 to a selected humanized template to obtain a humanized variable region, wherein the humanized variable region sequence is SEQ ID NO. 24, and the light chain variable region sequence is SEQ ID NO. 21; and then recombined with IgG constant region to form complete antibody. Meanwhile, the FR region in the V region of the humanized antibody is back-mutated, and exemplary back-mutation modes and combinations are as follows:

TABLE 5 mAb1901 humanized antibody and back-mutations^*

All amino acid positions in the table are numbered according to the Kabat numbering convention, and in N82T of the heavy chain variable region, 82 is position 82A according to the Kabat convention.

TABLE 6 mAb1901 humanized antibody light and heavy chain variable region sequences

The corresponding heavy chain variable regions in the table above may be compared to SEQ ID NO:7 to form the heavy chain of the full-length antibody, and the light chain variable region is connected with the heavy chain constant region of the human IgG1 shown in SEQ ID NO: the human kappa light chain constant region shown in fig. 8 is linked to form the light chain of the full-length antibody. In other embodiments, the heavy chain variable region and the light chain variable region can be linked to other heavy chain constant regions and light chain constant regions, respectively, to form a full-length antibody.

2.2 humanization engineering and Back-mutation design of mAb1902

Selecting a proper human antibody germ line, carrying out humanized transformation on the mAb1902 murine antibody, and transplanting the CDR region of the murine antibody mAb1902 to a selected humanized template to obtain a humanized variable region, wherein the humanized variable region sequence is SEQ ID NO. 31 and the light chain variable region sequence is SEQ ID NO. 28; and then recombined with IgG constant region to form complete antibody. Meanwhile, the FR region in the V region of the humanized antibody is back-mutated, and exemplary back-mutation modes and combinations are as follows:

TABLE 7 mAb1902 humanized antibody and back-mutation design thereof^*

All amino acid positions in the table are numbered according to Kabat numbering convention.

TABLE 8 mAb1902 humanized antibody light and heavy chain variable region sequences

The corresponding heavy chain variable regions in the table above correspond to SEQ ID NO:7 to form the heavy chain of the full-length antibody, and the light chain variable region is connected with the heavy chain constant region of the human IgG1 shown in SEQ ID NO: the human kappa light chain constant region shown in fig. 8 is linked to form the light chain of the full-length antibody.

Illustratively, the full-length sequence of the antibody is as follows:

chimeric antibody ch 1901:

ch1901 heavy chain: (SEQ ID NO:35)

ch1901 light chain (SEQ ID NO:36)

Chimeric antibody ch 1902:

ch1902 heavy chain (SEQ ID NO:37)

ch1902 light chain (SEQ ID NO:38)

TABLE 9 mAb1901 humanized antibodies

The full-length antibody light and heavy chain sequences are shown below:

TABLE 10 mAb1901 humanized antibody light and heavy chain sequences

TABLE 11 mAb1902 humanized antibody

The full-length antibody light and heavy chain sequences are shown below:

TABLE 12 mAb1901 humanized antibody light and heavy chain sequences

The positive control antibody of the present disclosure is IMAB-362 (from WO 2016166122):

IMAB-362 heavy chain (SEQ ID NO:53)

IMAB-362 light chain (SEQ ID NO:54)

The antibodies are cloned, expressed and purified respectively by using conventional gene cloning and recombinant expression methods.

In vitro biological evaluation of Activity

Test example 1: cell level ELISA binding assay

Cell-based ELISA assays were used to detect the binding properties of the claudin18.2 antibody. NUGC4 cells stably expressing Claudin18.2 were cultured in a 96-well cell plate (Corning, 3599), 4% paraformaldehyde was added to fix the cells for 1 hour after growth to 90% density, the plate was washed 3 times with PBST buffer (pH7.4 PBS containing 0.05% Tween-20), 200. mu.l/well of 5% skim milk (skim milk powder) blocking solution diluted with PBS was added, and the plate was incubated at 37 ℃ for 2.5 hours or left overnight (16-18 hours) at 4 ℃ for blocking. After blocking, the blocking solution was discarded, and after washing the plate 3 times with PBST buffer, 50. mu.l/well of the antibody to be detected diluted with a sample diluent (pH7.4 PBS containing 1% skim milk) at different concentrations was added and incubated in an incubator at 37 ℃ for 2 hours. After incubation, the plate was washed 5 times with PBST, 100. mu.l/well of HRP-labeled secondary goat anti-human antibody (Jackson Immuno Research, 109-. Washing the plate 6 times with PBST, adding 50 μ l/well TMB chromogenic substrate (KPL,52-00-03), incubating at room temperature for 10-15min, adding 50 μ l/well 1M H₂SO ₄The reaction was stopped and the absorbance was read at 450nm using an MD Versa Max (TM) microplate reader to calculate the binding EC50 value of the Claudin18.2 antibody to Claudin18.2 (results are shown in the table below).

TABLE 13 binding Activity of antibodies

Antibodies	IMAB362	ch1901	ch1902
Emax	1.175	1.399	1.272
EC50(nM)	0.108	0.098	0.074

TABLE 14-1 binding Activity of mAb1901 humanized antibody

Antibodies	Emax	EC50(nM)
IMAB362	1.115	0.086
h1901-2	1.039	0.076
h1901-3	1.1055	0.22
h1901-4	0.986	0.201
h1901-6	0.937	0.091
h1901-7	0.921	0.166
h1901-8	1.047	0.091
h1901-11	1.44	0.076
h1901-12	1.22	0.116

TABLE 14-2 binding Activity of mAb1902 humanized antibody

Antibodies	Emax	EC50(nM)
IMAB362	0.88	0.187
h1902-1	0.87	0.113
h1902-2	0.88	0.107
h1902-3	0.84	0.175
h1902-4	0.82	0.087
h1902-5	0.9	0.098
h1902-6	0.78	0.141
h1902-7	0.75	0.121
h1902-8	0.89	0.132
h1902-9	0.75	0.137
h1902-10	0.89	0.133

Test example 2: antibody cell level binding assay

Nugc4 cells stably expressing Claudin18.2 were prepared to 1 × 10 using FACS buffer (2% fetal bovine serum (Gibco, 10099141) pH7.4 PBS (Sigma, P4417-100TAB))⁶A cell suspension of 100. mu.l/well was added to a 96-well round bottom plate (Corning, 3795). After centrifugation, 50. mu.l/well of a solution of the Claudin18.2 antibody to be tested at different concentrations diluted in FACS buffer was added and incubated at 4 ℃ in the dark for 1 hour. After washing 3 times by centrifugation in FACS buffer 300g, Alexa Fluor 488-coated anti-human IgG (H + L) (invitrogen, A-11013) was added at working concentration and incubated in a refrigerator at 4 ℃ for 40 minutes in the absence of light. After 3 washes with 300g FACS buffer centrifugation, geometric mean fluorescence intensity was measured on a BD FACS cantonii flow cytometer and the binding EC50 value of the claudin18.2 antibody to NUGC4 cells stably expressing claudin18.2 was calculated, and the results are shown in fig. 1.

Test example 3: antibody endocytosis assay

The test Claudin18.2 antibody, pre-labeled Dylight 488NHS Ester (thermolisher, 46403), was added to a final concentration of 1X 10 at 5. mu.g/ml⁶The cells were incubated on ice for 1 hour in the dark, washed 3 times with precooled FACS buffer (pH7.4 PBS, 2% fetal calf serum), the supernatant was removed and the whole medium was added, and then incubated with 5% CO at 37 ℃ for 1 hour₂A cell culture box. The cells were removed after 0, 0.5, 1, 2, 4 hours, respectively, and stored on ice in the dark. After the samples were collected completely, the supernatant was removed by centrifugation at 300g at low temperature, and after adding an elution buffer (pH 1.70.05M glycine, 0.1M sodium chloride), the samples were incubated at room temperature for 7 minutes, washed by centrifugation at 300g of FACS buffer 1 time, and the geometric mean fluorescence intensity was measured on a BD FACS CantoII flow cytometer to calculate the efficiency of endocytosis of the Claudin18.2 antibody by NUGC4 cells stably expressing Claudin18.2. The results show (see fig. 2) that the humanized antibody has good endocytosis efficiency.

Test example 4: determination of antibody affinity based on flow cytometry

HEK293/hClaudin18.2 cells were harvested on the day of the experiment in U-bottom 96-well plates at 1X 10 per well⁵To 2X 10⁵And (4) cells. A starting concentration of 5. mu.g/ml, 2 Xgradient dilution (12 concentration points) of Claudin18.2 antibody was added and incubated at 4 ℃ for 1 hour with a positive control of IMAB362, while a negative control without antibody was set. After removing the antibody by centrifugation, 100. mu.l/well of FITC anti-human IgG Fc antibody (200X) was added, incubated at 4 ℃ in the dark for 30 minutes, washed twice with PBS + 2% FBS and ready for flow cytometry. Starting BD FACS CantoII, starting BD FACS diva software after preheating is completed, establishing a new experiment, detecting HEK293/hClaudin18.2 negative control samples, adjusting FSC and SSC voltage to appropriate values and storing. According to Quantum^TMFITC-5MESF Kit Specification, blank sample B and Standard Curve 1 were separately examined, and FITC voltage was adjusted to appropriate values and stored. Samples in U-bottom 96-well plates were tested at the stored voltage and data was recorded. Analyzing the experimental data by using Flowjo software to obtain a Geo Mean value according to Quantum^TMFITC-5MESF Kit instructions MESF-Geo Mean standard curves were fit, the molar concentration of Claudin18.2 antibody bound to HEK293/hClaudin18.2 cells and the free antibody concentration were calculated from the FITC anti-human IgG Fc antibody concentration fluorescence values, and Bmax and dissociation constant KD of the antibody were calculated using Scatchard mapping. The results are shown in Table 15.

TABLE 15 cellular level affinity of humanized antibodies

Antibodies	IMAB362	h1901-11	h1902-5
KD(nM)	10.2	6.8	1.64

Test example 5: evaluation of ADCC Effect of antibody

Various NUGC4 cells (high, medium and low expression Claudin18.2) were digested, centrifuged at 1000rpm, and then counted in a resuspension mode. Cells were cultured at 3X 10⁵The cells/ml were resuspended at density in phenol red free RPMI 1640 (Gibco, 11835-. In a 96-well plate (Corning,3903), 25. mu.l of cells (7500/well) were added per well. The antibody was diluted in the phenol red-free medium described above to prepare a 3 Xdiluted antibody solution, and 25. mu.l/well of the antibody was added to the cell plate. At 37 deg.C, 5% CO₂Incubate in incubator for 0.5 hours.

Effector cells (FcrR3A-V158-NFAT-RE-Jurkat cells) were harvested, centrifuged at 1000rpm, and resuspended for enumeration. Cells were cultured at 3X 10⁶The cells/ml density is resuspended in phenol red free RPMI 1640 supplemented with 10% FBS (New Zealand ultra-low IgG fetal bovine serum) and 25. mu.l cells (7.5X 10 cells) are added per well in the assay plate⁴Individual cells/well). At 37 deg.C, 5% CO₂Incubate in incubator for 6 hours.

To each well of the plate was added 75. mu.l/well of Bright-Glo (Promega, E2610) and chemiluminescence (luminescence) was detected with a microplate reader (Perkinelmer, VITOR 3).

The results show (see Table 16 and FIGS. 3A-3C) that both antibodies h1901-11 and h1902-5 show strong ADCC activity in NUGC4 cells expressing different degrees of Claudin18.2 in low and high.

TABLE 16 ADCC Effect of antibodies in NUGC4 cells with varying degrees of expression of Claudin18.2

Claims

An anti-claudin18.2 antibody comprising a heavy chain variable region and a light chain variable region, wherein:

i) the heavy chain variable region comprises a heavy chain variable region and a heavy chain variable region as set forth in SEQ ID NO:3, and a light chain variable region comprising HCDR1, HCDR2, and HCDR3 having the same sequence as the heavy chain variable region set forth in SEQ ID NO:4, LCDR1, LCDR2 and LCDR3 having the same sequence as the light chain variable region; or

ii) the heavy chain variable region comprises a sequence identical to the sequence set forth in SEQ ID NO:5, and a light chain variable region comprising HCDR1, HCDR2, and HCDR3 having the same sequence as the heavy chain variable region set forth in SEQ ID NO:6, LCDR1, LCDR2 and LCDR 3.
The anti-claudin18.2 antibody of claim 1, comprising a heavy chain variable region and a light chain variable region, wherein:

iii) the heavy chain variable region comprises the amino acid sequences as set forth in SEQ ID NOs: 9. SEQ ID NO: 10 and SEQ ID NO: 11 HCDR1, HCDR2, and HCDR3,

the light chain variable region comprises the amino acid sequences shown as SEQ ID NO: 12. SEQ ID NO: 13 and SEQ ID NO: LCDR1, LCDR2 and LCDR3 shown at 14; or

iv) the heavy chain variable region comprises the amino acid sequences as set forth in SEQ ID NOs: 15. SEQ ID NO: 16 and SEQ ID NO: the HCDR1, HCDR2 and HCDR3 shown at 17,

the light chain variable region comprises the amino acid sequences shown as SEQ ID NO: 18. SEQ ID NO: 19 and SEQ ID NO: LCDR1, LCDR2 and LCDR3 shown at 20.
The anti-claudin18.2 antibody of claim 1 or 2, which is a murine, chimeric or humanized antibody.
The anti-claudin18.2 antibody of any of claims 1 to 3, comprising a heavy chain variable region and a light chain variable region, wherein:

v) the heavy chain variable region having at least 90% identity in its amino acid sequence to SEQ ID NO 3 or 24, and

the light chain variable region having at least 90% identity in its amino acid sequence to SEQ ID NO 4 or 21; or

vi) the heavy chain variable region having an amino acid sequence at least 90% identical to SEQ ID NO 5 or 31, and

the light chain variable region having at least 90% identity in its amino acid sequence to SEQ ID NO 6 or 28;

preferably:

1) the heavy chain variable region has an amino acid sequence shown as SEQ ID NO. 3 or at least 90% identity with the heavy chain variable region, and the light chain variable region has an amino acid sequence shown as SEQ ID NO. 4 or at least 90% identity with the light chain variable region;

2) the heavy chain variable region has an amino acid sequence shown as SEQ ID NO. 24 or at least 90% identity with the heavy chain variable region, and the light chain variable region has an amino acid sequence shown as SEQ ID NO. 21 or at least 90% identity with the light chain variable region;

3) the heavy chain variable region has an amino acid sequence shown as SEQ ID NO. 5 or at least 90% identity with the heavy chain variable region, and the light chain variable region has an amino acid sequence shown as SEQ ID NO. 6 or at least 90% identity with the light chain variable region; or

4) The heavy chain variable region has an amino acid sequence shown as SEQ ID NO. 31 or at least 90% identity with the heavy chain variable region, and the light chain variable region has an amino acid sequence shown as SEQ ID NO. 28 or at least 90% identity with the light chain variable region.
The anti-Claudin18.2 antibody of claim 4, which is a humanized antibody comprising framework regions derived from a human antibody or framework region variants thereof having from 1 to 10 back mutations on the light chain framework region and/or the heavy chain framework region, respectively, of a human antibody;

preferably, the framework region variant comprises a mutation selected from a) or b) below:

a) the light chain variable region comprises one or more back mutations selected from 22S, 85I and 87H, and/or the heavy chain variable region comprises one or more back mutations selected from 48I, 82T and 69M; or

b) The light chain variable region comprises one or more back mutations selected from 4L and 22S, and/or the heavy chain variable region comprises one or more back mutations selected from 38K, 40R, 48I, 66K, 67A, 69L, 71L and 73K;

more preferably, the framework region variant comprises a mutation selected from a-1) or b-1) below:

a-1) a back mutation comprising 22S, 85I and 87H in the light chain variable region, and a back mutation comprising 48I and 82T in the heavy chain variable region; or

b-1) a back mutation of 4L in the light chain variable region;

in 82T of the heavy chain variable region, 82 is position 82A according to Kabat regulation.
The anti-claudin18.2 antibody of claim 3, comprising a heavy chain variable region and a light chain variable region as shown below:

vii) the heavy chain variable region sequence is shown in SEQ ID NO 3 and the light chain variable region sequence is shown in SEQ ID NO:4 is shown in the specification; or

viii) the heavy chain variable region sequence is set forth in SEQ ID NOs 24, 25, 26 or 27 and the light chain variable region sequence is set forth in SEQ ID NOs: 21. 22 or 23; or

ix) the heavy chain variable region sequence is shown as SEQ ID NO:5 and the light chain variable region sequence is shown as SEQ ID NO:6 is shown in the specification; or

x) the heavy chain variable region sequence is shown as SEQ ID NO 31, 32, 33 or 34 and the light chain variable region sequence is shown as SEQ ID NO: 28. 29 or 30;

preferably, the anti-claudin18.2 antibody, or antigen-binding fragment thereof, comprises a heavy chain variable region and a light chain variable region as shown below:

xi) the heavy chain variable region sequence is shown as SEQ ID NO. 31 and the light chain variable region sequence is shown as SEQ ID NO. 29; or

xii) the heavy chain variable region sequence is shown as SEQ ID NO. 26 and the light chain variable region sequence is shown as SEQ ID NO. 23.
The anti-Claudin18.2 antibody of any one of claims 1 to 6, further comprising a heavy chain constant region and a light chain constant region;

preferably, the heavy chain constant region is selected from the group consisting of human IgG1, IgG2, IgG3, and IgG4 constant regions, and variants thereof,

preferably, the light chain constant region is selected from human antibody kappa and lambda chain constant regions and variants thereof;

more preferably, the anti-Claudin 18.2 antibody comprises a heavy chain constant region as set forth in SEQ ID NO. 7 and a light chain constant region as set forth in SEQ ID NO. 8;

most preferably, the anti-claudin18.2 antibody comprises: a heavy chain having at least 90% identity to SEQ ID NO 35 or 42 and a light chain having at least 90% identity to SEQ ID NO 36 or 39; or

A heavy chain having at least 90% identity to SEQ ID NO 37 or 49 and a light chain having at least 90% identity to SEQ ID NO 38 or 46.
The anti-claudin18.2 antibody according to any of claims 1 to 7, comprising:

c) 35 and the heavy chain of SEQ ID NO:36, a light chain;

d) 42, 43, 44 or 45 and the heavy chain of SEQ ID NO: 39. 40 or 41;

e) 37 and the heavy chain of SEQ ID NO: 38; or

f) 49, 50, 51 or 52 and the heavy chain of SEQ ID NO: 46. 47 or 48.
The anti-claudin18.2 antibody of any of claims 1 to 8, comprising:

the heavy chain shown as SEQ ID NO. 44 and the light chain shown as SEQ ID NO. 41; or

The heavy chain shown as SEQ ID NO. 49, and the light chain shown as SEQ ID NO. 47.
An isolated anti-claudin 18.2 antibody that competes for binding to human claudin18.2 with the anti-claudin 18.2 antibody of any one of claims 1 to 9.
A nucleic acid molecule encoding the anti-claudin18.2 antibody of any of claims 1 to 10.
A host cell comprising the nucleic acid molecule of claim 11.
An antibody drug conjugate formed by coupling the anti-claudin18.2 antibody according to any one of claims 1 to 10 with a cytotoxic drug.
A pharmaceutical composition comprising a therapeutically effective amount of an anti-claudin 18.2 antibody according to any one of claims 1 to 10, or a nucleic acid molecule according to claim 11, or an antibody drug conjugate according to claim 13, and one or more pharmaceutically acceptable carriers, diluents, buffers or excipients.
A method for immunodetection or assay of claudin18.2, the method comprising:

a step of contacting the anti-claudin18.2 antibody according to any of claims 1 to 10 with a sample to be tested.
A kit comprising an anti-claudin18.2 antibody according to any of claims 1 to 10.
A method of treating a disease associated with claudin18.2, said method comprising administering to a subject a therapeutically effective amount of an anti-claudin 18.2 antibody of any one of claims 1 to 10, or a nucleic acid molecule of claim 11, or an antibody drug conjugate of claim 13 or a pharmaceutical composition of claim 14, preferably said disease is a tumor;

more preferably, the disease is selected from: squamous cell carcinoma of head and neck, cancer of head and neck, brain cancer, glioma, glioblastoma multiforme, neuroblastoma, central nervous system cancer, neuroendocrine tumor, laryngeal cancer, nasopharyngeal cancer, esophageal cancer, thyroid cancer, malignant pleural mesothelioma, lung cancer, breast cancer, liver cancer, hepatoma, hepatocellular carcinoma, hepatobiliary cancer, pancreatic cancer, gastric cancer, gastrointestinal cancer, intestinal cancer, colon cancer, colorectal cancer, renal cancer, clear cell renal cell carcinoma, ovarian cancer, endometrial cancer, cervical cancer, bladder cancer, prostate cancer, testicular cancer, skin cancer, melanoma, leukemia, lymphoma, bone cancer, chondrosarcoma, myeloma, multiple myeloma, myelodysplastic syndrome, kunkenberg's tumor, myeloproliferative tumor, squamous cell carcinoma, ewing's sarcoma, systemic light chain amyloidosis, and merkel cell carcinoma;

more preferably, the lymphoma is selected from: hodgkin's lymphoma, non-hodgkin's lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, primary mediastinal large B-cell lymphoma, mantle cell lymphoma, small lymphocytic lymphoma, large B-cell lymphoma rich in T-cells/histiocytes, and lymphoplasmacytic lymphoma;

the lung cancer is selected from: non-small cell lung cancer and small cell lung cancer;

the leukemia is selected from: chronic myeloid leukemia, acute myeloid leukemia, lymphocytic leukemia, lymphoblastic leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, and myeloid leukemia.